Soft springs and Koni's?

I'm installing a suspension today into a 96 RMS with the V92 springs ( the trailer towing spring which GM charts as one step stiffer than the 9C1 spring while sitting lower. I've measured the spring install at 27" front and 20 1/4 " rear with a 27.1" diameter tire) The goal is a softer riding RMS than the one with Eibach springs (Ron's former car, a 95 RMS, both white!). Airlift #60755. ZQ8's, 35mm (1 3/8 ) F+R sways, UMI #3615-B LCA's, DMR 5029-W rear frame braces, Koni 1087-1088 shocks. I'm going to adjust the Koni's half way to between full soft and full hard, expecting that to keep things soft I'll have to readjust then toward full soft. Has anyone here ever used soft springs like these (compared to aftermarket lowering springs) with Koni's?

I have these shocks in my 88 Caprice LS Brougham. First installed with OEM luxury springs and Koni's set to the softest click, tried the next firmer click and found the car was a bit harsher on fast road irregularities.

Changed rear springs to a higher rate set, but delivering the same ride height, and found that it ruined the "nice ride" on the highway, , both on dips, swells and bumps.
Turns out I mismatched the front to rear natural ride frequency, and it could NOT be remedied with shock settings. Too much "pitch - pitch jerk".

Ordered/installed the Eibach "Made in Germany" matched set Sport springs, and test drove the car with no shocks in it only to discover a nice F to R balance had returned.
I put the shocks back in and started out at the Koni's softest click setting, and subsequently found the next firmer click was an improvement.
Next, I selected the next firmer click up but that same harshness returned slightly, so I reset them back to the second softest click.

I imagine that if the shocks become softer with age & use (abuse), I could retry the firmer click setting to make up for wear related "looseness".
Be aware that even though stiff sway bars have no effect on road dips, they do have a huge effect on harshness anytime one wheel finds a bump or dip, as that will upset the smoothness greatly.

My car has a full set of new upper & lower GM body mount bushings as per 96 9C1, and a boxed, gusseted & triangulated chassis for considerably increased torsional rigidity, but the issue HERE is "soft ride versus firm ride".
It also has H.A. front "nyliner" control arm bushings and rear Global West's LCAs with H.A. sway bars F & R.
I believe that very often some "fix" is applied to remedy a ride or handling issue that missed the actual cause, and at best is a band-aid that further disguises a real problem elsewhere.

My only additional point to raise here is that you may not like the loss of "Flat-Ride" smoothness if you disregard front to rear natural "bounce frequency", and wind up with a badly mismatched F to R frequency ratio.
If that ratio is not provided for you somewhere, its easy enough to figure out on your own.
Its actually MUCH easier to determine on a SOFTLY sprung car, because slower oscillations are easier to see and count.
It is to be checked with all four shocks removed from the car, then you time the F and R bounce rates in "cycles per minute" by bouncing the car one axle at a time.

Its entirely possible to loose some very important ride characteristics without even realizing it, especially when such a loss is caused by effects that can be from an often neglected and possibly "counter-intuative" origin.

.

I greatly appreciate your input. I've also learned the hard way about " natural "bounce frequency", and wind up with a badly mismatched F to R frequency ratio." Global west front springs and 9C1 rear springs gave a level height of about 28" all around, but the "bounce frequency' was so far off as too ruin the handling under most conditions. The now discontinued Eibach #3832.140 for the Caprice had a rear spring that sat .3" higher in static height than the Impala SS Eibach kit #3837.140. I felt it was the perfect choice for B-body cars, even the wagons. So using almost new V92 springs is an experiment to see if a more "cushy" ride is possible with out giving up too much of what the Eibach kit gave. There was also a dedicated Eibach part number for the RCMP #3833, identical to the #3832, all gone now.

What I know so far is that the greater wheel travel the springs give also require a lot of control for those springs. I find the 1 1/2" rear HA bar has too much roll resistance at high speed, though it's very usable in low speed, smooth course autocross. So I'm using a 1 3/8 rear bar and a matching 1 3/8 front (like the solid front HA, this one from Malibu Performance, the rear a solid bar from Quickor Suspension, both companies also gone. There are new 1 3/8 hollow bars available now with almost identical roll stiffness to the solid bars because they are shorter.) With 255/50-17's, the front has settled at 27 3/4" and the rear at 21.0, using Airlifts with only 5 L and 9 R pounds of air. The ride is very comfortable, much more "cushy" than Eibach's give, but the overall handling is also somewhat less capable. I'll be adding more rebound to at least the front shocks, but the rears at the half way to full hard point are just about right. Even with less than ideal settings on the shocks, the car is very neutral and rotates wonderfully. These are the wheels and tires from my 95 T-56 RMS which now has 275/40-17 RE760's. At 25.7", I don't think I want to use them on the high riding 96, but it could stand a wider tire.
Maybe the 275/60-15's and 295/50-15's on widened 15x8.5 Caprice Alloys? JUST KIDDING!
One surprise is that the ZQ8's don't even touch the frame. Nick has suggested that I might be better off going back to bump stops and keeping all the suspension travel, so I'll try that too along with more rebound in the front.

Wow, I feel I'm not quite in the league of this conversation.

Good info here. Too bad a bunch of that stuff is discontinued.

I love my 295/50/15's and 255/60's on 15x8" rallyes.

Seems like Ron's old ride went into capable hands. Hope to see ya stick around, Scot!

I found the last set of wagon specific eibach springs for the blue wagon,. and then added a set of the bilstein 929/1104 shocks,. i,m so pleased with the way that car rides even lowered 2". The eibachs are a very fast progressive rate,. yet give an impressive ride when utilizing the first inch of travel or so, but tighten up nicely as more chassis dynamics come into play,. The bilsteins have the strength to control them,.the big brakes work well yet the car doesn't dive very much unless in an extreme braking situation. The black wagon,. i added a set of lowering springs i,m not sure of the brand, they were a cheap deal,. and i hated the cars ride,. it pogo'd all the time even with monroe hd gas shocks,. so i replaced the fronts only with a set of stock wagon springs,. the car sits dead level which doesn't look that great,. but the ride quality improved dramatically,.nno more front to rear pogo 'ing
i,m planning to cut 1/2 a coil of the front springs to lower it ever so slightly,.i,m hoping that the monroe's can handle the increased spring rate,. The rears are still the cheap lowering springs with wore out old shocks,. and that gives a great ride,. but leaves chassis dynamics a lot to be deisired in spirited cornering,. so i try to avoid taking a corner at 1/2 speed so to speak,. i either drive it gently around the corner or toss it in hard and it squats down and i then try to carry that all the way thru till the exit,.
Adjustable shocks are the way to tailor a cars ride,.adjustable to the spring rates compression and rebound,. and can be tailored for individual preference.
Too large of a sway bar will toss the car around on harsh sloped crowns in the road,. so again everything needs to work together as a combo,.
ZQ8 bump stops were not designed to increase spring pressure,. but as an anti dive stop gap,.if the suspension is soft enough to come into contact with the zq8's then it will be like driving a barn cart as they effectively almost remove any spring action of the suspension components,.

Nick
jm2c

"I love my 295/50/15's and 255/60's on 15x8" rallyes. "

With the Caprice alloy's widened to 15x8 1/2, I'd love to use 255/60-15's front and 295/50-15's rear. BUT... speaking of discontinued parts, there are no really modern construction tires, like the Potenza RE760's now on my T-56 RMS or something like a Pirelli P-Zero, any longer made in those sizes. I have 4 V rated Firestone Firehawk Pursuit Vehicle 235/70-15's in excellent shape @ 28" tall and a 275/60 @ 28" would be a perfect match IF I could find them in a Firehawk. Or 4 tires @ the 295/50-15 height. No chance. BFG still has the old style T/A, but it's not in the same league with the new construction stuff, and that's as close as I can come. High Performance 15" tires are the 33 1/3 records of 2011.
So 17's x 8 1/2 wheels are my starting point with the take-off's from my T-56 RMS. With the nitrogen filled 255/50-17 Kuhmo's I'm able to use about as soft riding a modern tire as I'm likely to find.

"Adjustable shocks are the way to tailor a cars ride,.adjustable to the spring rates compression and rebound,. and can be tailored for individual preference.
Too large of a sway bar will toss the car around on harsh sloped crowns in the road,. so again everything needs to work together as a combo,.


Nick
jm2c[/quote]

The Koni 1087-1088 is rebound adjustable only. The compression is factory set and surprisingly compliant. Full soft provides a very compliant ride and that compression rate never changes, even set full stiff. Set halfway between full soft and full stiff, they have a lot of control, all the rear can handle. Fronts are yet to be determined.
I've used as large as a 1 1/2 inch solid sway bar at the front end of the car, and found that unless the front frame is reinforced a lot, the 1 1/2 bar will bend the frame rails. The bar fits by being offset down from the frame by 1 1/2 inch spacers. Not healthy for the stock frame but with a cross member added between the front frame rails, and a honeycombed and seam welded boxed frame, it feels very good with just a slight bias toward understeer when using a solid 1 3/8 rear bar. That rear bar is bent like a OEM bar, not the HA style which is shorter (the HA, HO, BMR or any similar solid rear bar is 406% stiffer than the FE2 stock 1 1/16 rear bar). Even with that 1 1/2 front I've found the 1 1/2 rear bar is less balanced than the rear 1 3/8 solid. Those combinations work best with OEM Impala SS springs. I still have this boxed and seam welded 94 SS set up this way on Pirelli P-Zero's and it's my benchmark for ultimate handling. A 1 1/2 hollow bar, or a solid bent like the OEM bar, MIGHT be best for balancing a 1 1/2 front, but there is no such thing. The good news is that there are now hollow 1 3/8 front and rear bars available.
GM deliberately biased toward understeer by using 1/8 inch smaller rear bars than front. (FE2 uses 1 3/16F and 1 1/16R) I've found using the same diameter currently available F+R bars to be most neutral regardless of the spring set that's used.

phantom 309 wrote:

I found the last set of wagon specific eibach springs for the blue wagon,.

Nick
jm2c

If you use the Eibach Impala SS #3837.140 on a B-body wagon, here's what happens. Because the extra overhang at the rear of the wagon cantellievers the weight bias, installed the Eibach's create a weight distribution of 51% F and 49% R. Measured on a truck scale, static weight with just front, then rear on the scale. I recorded 27 1/8 F and 20 1/8 R using a 27.1" tall tire and Airlift #60733 5psi left and 7psi right. Handled just like a stock Impala SS. Really, and no one more surprised than me.

I have the Firestone Firehawk Indy 500's on there and they are probably the nicest set of tires I've owned. Ride nice in the dry and rain, great traction on the autoX and drag strip, too!

Tire Rack says that the Firehawk Indy 500 in 295/50-15 will be produced again by 9/20/11. The 275/60-15 will be produced 8/02/11. I have more options than I thought.

Trying to stay focused on the theme of soft springs & Konis, for a nice ride.
My concern is how to answer these questions: What constitutes a nice ride? at what ride height? on what range of road surfaces? at what range of speeds? carrying how much additional load?
Scot is correct, Konis are only adjustable in rebound. They are also linearly damped.
Bilsteins mentioned are not adjustable, but are digressively damped, so they should be smoother hitting bumps at higher speeds, yet still plant the tires on smooth corners and at highway speeds.
The best shock I've actually bought and played with was the single adjustable Vari-Shock (also digressive valving). I wanted the dual adjustable version but they were out of my budget.
Unless someone comes up with an affordable quad adjustable unit that fits my SS, I will get the Vari-Shock dual adjustables next time.

Thoughts on ride determinant factors: Tires are "springs" too, only there's no way to mount a shock between the LCA or axle and the ground!
I think of the vehicle as having the unsprung mass (axle, wheels-[not tires], brakes, spindle, etc.) being compression stacked or "suspended" between the road and the vehicle's "sprung" mass, where the tire is the spring below and the coil springs are above.
The typical quarter car unsprung mass would be around 100 lbs and the sprung weight on the same corner might be around 1,000 lbs.
The wheel CPMs will be much higher (600-700) than the vehicle CPMs (60-90).
The ride quality must derive from the tire choice, spring selection and shock choice (and it's setting if adjustable).
I have to believe there is a difference of wheel frequency rate between comparing a 235/70R15 and a 295/45ZR18 on the same test vehicle, apples to apples. Be like changing springs to some extent.
Shocks need to manage cornering tire behavior, launching and braking, while not producing a harsh ride quality.
Increases of shock dampening curves always approach harshness, and for comfort, those curves should be matched to just meet the required value, 25% of critical has been considered standard point of deviation.

Much good research & development has been done on where to locate the "Spring center" in relation to CofG and wheel base and at what relative frequencies are thought to be comfortable for "Flat Ride".
It should be mentioned that high sway bar lateral stiffness will negatively affect the balance between F to R pitch frequency and roll frequency. They should be very close in CPMs for a good natural ride.
The chassis and it's torsional stiffness as well as how rigidly it is attached to the body will determine yet another resonant mass that contributes to ride quality.
Thats why the factory left out three lower body mount bushings per side on the SS as compared to the 9C1.
The chassis will flap around quite a bit going over rough road surfaces at speed, and the SS was considered a luxury personal vehicle and they wanted to better isolate the cabin from NVH.

I have not found variable rate springs (front &/or rear) to be as good or better than linear rate springs in my testing.
They do provide a softer ride with the added benefit of increased safety against bottoming out, especially with any extra load onboard.
I would like to find true "constant rise" variable rate springs in the correct ride height & firmness range for my needs. [A gradual steady change in helix angle over it's entire length].
The variable rate springs I have seen and tried so far that might meet my needs have been three tight coils on top of three open coils, causing a sudden and upsetting rise in spring rate upon partial coil-bind.

Another few words on sway bars, rear LCA mounted bars are far from ideal. It really needs to be frame mounted with links to the axle, but second choice would be pivoted on the axle like on F-bodies.
The problems aside from kinematic binding are that they are way too heavy in order to be effective with a 21.9" long LCA, and they are not adjustable (such as with multiple end-link holes).

Does any body have a really cool way to accurately measure front and rear bounce frequency on their suspension?
I remove the shocks, attach a coat hanger wire from my license plate screw to strike a flexible plastic card that is lodged between cinder blocks stacked close to the bumper.
Carefully I bounce just one end of the car at a time to "click" the card (like baseball cards in your bicycle spokes).
I use my metronome to "sync" with the clicks to determine my CPMs, (cycles per minute).

OK thats it.......I'm on overload.
Prior to now, I condsidered myself reasonably intelligent.
Now, I've given up hope for suspension happiness, or at least grasp of same.
Our choices are limited, can we work with specifics instead of theory?
i.e I used Hotchkiss springs with single adjustable Vari-shocks? FTW?
I'm thrilled to see we have such advanced thinkers on the job, but I cant follow.
.......OK thats my vent......carry on

sdstick wrote:

OK thats it.......I'm on overload.
Our choices are limited, can we work with specifics instead of theory?
i.e I used Hotchkiss springs with single adjustable Vari-shocks? FTW?

Hotchkis stuff is VERY well made and you certainly made an excellent choice in shocks.
I forgot to mention that the single adjustable Vari-Shocks have 16 settings that actually set both compression and rebound proportionately with every setting.
That means they are technically dual adjustable shocks, but just not independently so.

I didn't mean to put anybody into M.E.G.O. mode! (see below)

My process: Define the desired outcome!
1) research whats readily available first, and find out whats being promised in delivered performance.
2) find out if theres enough reason to believe in the factuality of that promised performance.
3) see if there is another (cheaper) way to achieve similar or better results independently of buying parts.
4) learn how to measure, gather, and interpret the most pertinent data that was accurately obtained.
5) develop a first strategy for steps toward my goal after initially measuring all the baseline data.
6) change one thing at a time. measure and compare data for analysis upon each change.
7) repeat & repeat again until you one day wake up and bang your forehead on a pine box lid!

It certainly does require much patience, but its NOT hard to do or understand.
It's not about intelligence, it's much more to do with perseverance.
Success (or genius) is 1% inspiration and 99% perspiration.

My Eyes Glaze Over

Machine-De-Zine wrote:

I didn't mean to put anybody into M.E.G.O. mode!

It's not about intelligence, it's much more to do with perseverance.
Success (or genius) is 1% inspiration and 99% perspiration.

My Eyes Glaze Over

I think I'd be better off grasping this suspension subject in a bench racing environment.
Please dont let my post stop this exchange, I'm TRYING to keep up

[quote="sdstick"]OK thats it.......I'm on overload.
Now, I've given up hope for suspension happiness, or at least grasp of same.
Our choices are limited, can we work with specifics instead of theory?

Fair enough...try this
Spring rate is a variable worth controlling. Even the frame has spring rate as it flexes and twists, so as rigid as possible a frame is valuable, but cost becomes silly really fast. A carbon fiber frame would help any B-body, but cost is absurd, so boxing the frame, seam welding, DMR frame braces, a "Buick brace" style crossmember or honeycombing are cost effective but structurally limited ways to make the frame less uncontrolled. 1 1/2' front sway bars will bend a stock frame with every move, so weld a crossmember just where the oem sway bar mounts, honeycomb the front frame rails, then mount the bar with spacers directly below that CM and even a 1 1/2" bar flexes the frame a lot less. So you get a lot less spring rate variable from the frame. Even this labor cost is probably not cost effective unless you do it yourself.
I've found using the same diameter bars at both ends of the car to be best for controlling the side to side spring rate variable, all else being equal. So if the bar is as long as an oem bar, solid and bent like oem, then ie. a 1 1/4 bar front and rear will greatly help to balance the understeer built in oem. Even a 1" bar at both ends would, but with more body roll. It gets complicated when bars are not bent like oem (HA is a good example) or hollow (like Hotchkis bars) or shorter (again HA, or HO or BMR) or longer (Hotchkis or HA front). Longer bars =softer, more bends = softer, hollow =softer, all else being equal. All solid steel is unvarying in spring rate, always a fourth power equation based on diameter. At both ends, both 1 1/2 solid bars induce too much spring rate for 99.9% of the B-body cars out there.
Shocks and springs are even more complicated. IE...Vari-rate shocks adjust both comp +rebound with each adjustment and they are too stiff in compression long before they are stiff enough in rebound, no matter how you adjust them. This only applies to B-body cars with any currently available spring set. One reason why I now use Koni's exclusively, is these cars require really very little comp and lots of rebound, which Koni's can give.

Our choices are limited, can we work with specifics instead of theory?

[/quote]

This might sound familiar but while there are an infinite number of "good" choices for a B-body, I consider this "best" of what is currently available for a stock frame and SS wheels car...
275/40-17's summer only tires or 255/50-17 all season
Eibach #3837.140 springs
AirLift # 60733 with seperate fill lines
Koni #8040-1087 and 8040-1088 shocks, adjusted to the halfway point front, somewhat less rear, possibly full soft on the summer tires.
UMI #3615-B LCA's chosen because they are boxed and cost effective, others with matched UCA and flexible attachment points can work well too but for the added costs the cost/benefit ratio goes down.
Hellwig #55720 Hollow front sway bar @ 1 3/8 diameter (35mm)
Hotchkis #2205R Hollow rear sway bar @ 1 3/8 diameter (35mm)
DMR #5029-W Rear frame braces
ZQ8's, possibly cut down to almost bump stop height, or not depending on where the springs settle.

On a wagon, delete the DMR's and try to get a used Hotchkis wagon bar, which will be 1 1/4 solid, which is almost identicle in roll stiffness to the 1 3/8 hollow.

scot wrote:

Our choices are limited, can we work with specifics instead of theory?

Scot wrote:
This might sound familiar but while there are an infinite number of "good" choices for a B-body, I consider this "best" of what is currently available for a stock frame and SS wheels car...
275/40-17's summer only tires or 255/50-17 all season
Eibach #3837.140 springs
AirLift # 60733 with seperate fill lines
Koni #8040-1087 and 8040-1088 shocks, adjusted to the halfway point front, somewhat less rear, possibly full soft on the summer tires.
UMI #3615-B LCA's chosen because they are boxed and cost effective, others with matched UCA and flexible attachment points can work well too but for the added costs the cost/benefit ratio goes down.
Hellwig #55720 Hollow front sway bar @ 1 3/8 diameter (35mm)
Hotchkis #2205R Hollow rear sway bar @ 1 3/8 diameter (35mm)
DMR #5029-W Rear frame braces
ZQ8's, possibly cut down to almost bump stop height, or not depending on where the springs settle.

On a wagon, delete the DMR's and try to get a used Hotchkis wagon bar, which will be 1 1/4 solid, which is almost identicle in roll stiffness to the 1 3/8 hollow.[/quote]

Machine-De-Zine wrote:
Awesome recommendations there, I have to admit.
As we are drifting off of the "soft ride" theme to respond to a valid "specifics" vs "theory" observation,

If I may suggest, , , but for just a bit more coin, , ,
275/40ZR17s summer hi-perf tires
Canuck part # 2127.42100 all 4 springs 1.5" drop, 690F & 240R linear rate
VariShock Front, VAS 14145-515 and Rear, VAS 14169-715 (digressively valved)
UMI # 2034 Fixed Dual Roto-Joint rear LCAs (no sway-bar holes)
Hellwig Front sway-bar # 5720 solid 4140 1.3125" (better tire clearance)
Hellwig Rear sway-bar # 5802 adjustable axle mounted 1.0"
Pro-Touring F-Body OCF - 801 X 12 Solid body mounts
DMR #5029 braces & Buick rear "buzz bar"
ZQ8s @ full height.
Acetron (nylon) front lower control arm bushings
Max out front caster (+6-9), Howe tall UBJ & -1 degree camber.

Spend more $ for a tighter, smoother and faster ride.
Of course there is MUCH more that can be done,
but this would be a very nicely integrated DD package.

And if you are going to spend more money, then do the frame.
Three of my cars have a fully seam welded, boxed, honeycombed frame with added cross members front and rear. I can't quantify if or how much this modification improves the handling of the cars. Makes sense that it does something positive but the real, dramatic difference is in perception. All of them feel more immediate with faster steering inputs and an agility that makes them feel feline quick while also feeling like a much heavier, all of one piece, car. Heavier in the "chiseled from a block of stone" sense, while driving like a smaller, lighter car in agility. My 94 Impala was built by Specialty Vehicles International, a Colorado firm, long gone, that started exporting modified 94 Impala's to the middle east for $100,000. There first step was to remove the body to do the frame as I wrote above, then install 4.10's, T-56, Paxton SC and a jillion other parts for rear wheel HP of 385 to 555HP. My 94 has 33,000 miles on it and drives like a brand new AMG, at 18 years old. Guy who sold it to my father was getting divorced and sold it to him for $15,000 with two sets of SS wheels. Better to be lucky than good. That car convinced me to do my own welding on my other cars.